Acoustic characteristics of forage fish species in the Gulf of Alaska and Bering Sea based on Kirchhoff-approximation models

2004 ◽  
Vol 61 (10) ◽  
pp. 1839-1850 ◽  
Author(s):  
Stéphane Gauthier ◽  
John K Horne
Keyword(s):  
Fish Species ◽  
Bering Sea ◽  
Gulf Of Alaska ◽  
Target Strength ◽  
Fish Length ◽  
Acoustic Characteristics ◽  
Capelin Mallotus Villosus ◽  
Variance Estimates ◽  
Atka Mackerel ◽  
Pleurogrammus Monopterygius

Acoustic surveys are routinely used to assess fish abundance. To ensure accurate population estimates, the characteristics of echoes from constituent species must be quantified. Kirchhoff-ray mode (KRM) backscatter models were used to quantify acoustic characteristics of Bering Sea and Gulf of Alaska pelagic fish species: capelin (Mallotus villosus), Pacific herring (Clupea pallasii), walleye pollock (Theragra chalcogramma), Atka mackerel (Pleurogrammus monopterygius), and eulachon (Thaleichthys pacificus). Atka mackerel and eulachon do not have swimbladders. Acoustic backscatter was estimated as a function of insonifying frequency, fish length, and body orientation relative to the incident wave front. Backscatter intensity and variance estimates were compared to examine the potential to discriminate among species. Based on relative intensity differences, species could be separated in two major groups: fish with gas-filled swimbladders and fish without swimbladders. The effects of length and tilt angle on echo intensity depended on frequency. Variability in target strength (TS) resulting from morphometric differences was high for species without swimbladders. Based on our model predictions, a series of TS to length equations were developed for each species at the common frequencies used by fisheries acousticians.

scholarly journals Potential acoustic discrimination within boreal fish assemblages

2004 ◽  
Vol 61 (5) ◽  
pp. 836-845 ◽  
Author(s):  
Stéphane Gauthier ◽  
John K. Horne
Keyword(s):  
Fish Species ◽  
Fish Assemblages ◽  
Scattering Length ◽  
Morphological Variability ◽  
Gulf Of Alaska ◽  
Target Strength ◽  
Fish Length ◽  
Acoustic Discrimination ◽  
Capelin Mallotus Villosus ◽  
Species Specific

Abstract Differences in the acoustic characteristics of forage fish species in the Gulf of Alaska and the Bering Sea were examined using Kirchhoff ray-mode (KRM) backscatter models. Our goal was to identify species-specific characteristics and metrics that facilitate the discrimination of species using acoustic techniques. Five fish species were analyzed: capelin (Mallotus villosus), Pacific herring (Clupea pallasii), walleye pollock (Theragra chalcogramma), Atka mackerel (Pleurogrammus monopterygius), and eulachon (Thaleichthys pacificus). Backscatter amplitude differences exist among these species, especially between swimbladdered and non-swimbladdered fish. Echo intensities were variable within and among species. The effect of morphological variability was indexed using the ratio of the Reduced-scattering length (RSL) standard deviation over its mean. Morphological variability was low only at fish length to acoustic wavelength ratios less than eight. Target strength differences between pairs of carrier frequencies (ranging from 12 kHz to 200 kHz) differed among species, and were dependent on fish size and body orientation. Frequency differencing successfully discriminated between fish species but the choice of frequency to maximize target strength differences was not consistent among species pairs. Frequency-dependent, backscatter model predictions facilitate comparison of target strength differences prior to acoustic data collection.

scholarly journals STATE OF STOCKS AND MODERN FISHERY OF ATKA MACKEREL PLEUROGRAMMUS MONOPTERYGIUS (PALLAS, 1810) IN THE OLYUTORSKY-NAVARINSKY AREA OF THE BERING SEA

2020 ◽  
Vol 200 ◽  
pp. 38-57
Author(s):  
A. O. Zolotov ◽  
O. G. Zolotov ◽  
Yu. K. Kurbanov
Keyword(s):  
Bering Sea ◽  
Gulf Of Alaska ◽  
Aleutian Islands ◽  
Commander Islands ◽  
Spawning Grounds ◽  
Spawning Stock ◽  
Atka Mackerel ◽  
Pleurogrammus Monopterygius ◽  
Commercial Stock ◽  
The Bering Sea

Atka mackerel Pleurogrammus monopterygius is one of the mass species of fam. Hexagrammidae that inhabits the boreal and subarctic waters of the North Pacific and forms two large populations in its western and eastern parts. Reproductive range of the eastern, Aleutian population extends from the Gulf of Alaska, along Aleutian Islands to Commander Islands, with the main spawning grounds at the Aleutians and in the southeastern Bering Sea. From these areas, the fish at early stages of ontogenesis spread widely in system of the Bering Sea currents to the western-southwestern Bering Sea, where the atka mackerel aggregations are formed on the external shelf at prominent capes, as Cape Olyutorsky. Dynamics of the atka mackerel stock in the Olyutorsky-Navarinsky area in 1994–2019 is presented on the base of bottom trawl surveys, fishery statistics, and open NOAA data. After the period of low stock in the middle 1990s, the atka mackerel abundance increased sharply to the maximum in 2006–2008, when the spawning stock in this area was about 9.5 . 103 t and the commercial stock about 14.0 . 103 t. Since that time, trend to decreasing is observed, with the spawning stock 3.6 . 103 t and the commercial stock 5.6 . 103 t in 2013, and recent stabilization at the low level with slight decline continuing. A possible reason of the sharp increase in 2000s could be the intensive transport of the atka mackerel juveniles from the main spawning grounds at Aleutian Islands to the area at Cape Olyutorsky. The catches of atka mackerel in the Olyutorsky-Navarinsky area in 1994–2018 corresponded well with its stock dynamics.

scholarly journals Examining the ecological role of jellyfish in the Eastern Bering Sea

2019 ◽  
Vol 77 (2) ◽  
pp. 791-802 ◽  
Author(s):  
James Ruzicka ◽  
Richard D Brodeur ◽  
Kristin Cieciel ◽  
Mary Beth Decker
Keyword(s):  
Bering Sea ◽  
Gulf Of Alaska ◽  
Forage Fish ◽  
Eastern Bering Sea ◽  
Gadus Macrocephalus ◽  
Northern California Current ◽  
Capelin Mallotus Villosus ◽  
Northern Pacific ◽  
Negative Impacts

Abstract Within the Eastern Bering Sea, the jellyfish Chrysaora melanaster has fluctuated widely over recent decades. We examined the role of C. melanaster as an ecosystem-structuring agent via application of ecosystem models representing inner-, mid-, and outer-shelf regions of comparable areal coverage. Chrysaora melanaster utilize 1% of total mid-shelf consumer production, or 1/4th the energy required by forage fish (capelin Mallotus villosus, Pacific herring Clupea pallasii, age-0 Pacific cod Gadus macrocephalus, age-0 walleye pollock Gadus chalcogrammus). Model simulations show the impacts of C. melanaster are broadly distributed across consumer groups with increasingly negative impacts with higher jellyfish biomass. Age-0 pollock represent the greater part of the forage fish biomass, and observed pollock biomass during low jellyfish years (2004–2007) was significantly greater than during high jellyfish years (2009–2014). However, sensitivity among consumer groups to observed jellyfish variability is small, within 5% of baseline (2004–2015) conditions. Estimates using similar models for the Coastal Gulf of Alaska (CGoA) and Northern California Current (NCC) suggest large differences in the role of scyphozoans among northern Pacific shelf ecosystems. Only 0.1% of total summer consumer production is required to support CGoA Chrysaora, while the coastal NCC population uses 19%.

Estimating target strength of young chum salmon (Oncorhynchus keta)

2022 ◽  
pp. 1-5
Author(s):  
Kenji Minami ◽  
Hokuto Shirakawa ◽  
Yohei Kawauchi ◽  
Huamei Shao ◽  
Makoto Tomiyasu ◽  
...  
Keyword(s):  
Bering Sea ◽  
Chum Salmon ◽  
Fork Length ◽  
Target Strength ◽  
Oncorhynchus Keta ◽  
Biomass Estimation ◽  
Fishery Resource ◽  
Chum Salmon Oncorhynchus Keta ◽  
Acoustic Methods ◽  
The Bering Sea

Although chum salmon (Oncorhynchus keta) is an important fishery resource in Japan, acoustic methods cannot be applied to biomass estimation because the target strength (TS) is unknown. This study clarified the TS for each fork length (FL: 5.5–33.5 cm) of young chum salmon inhabiting the Japanese coastal area to the Bering Sea by measuring free-swimming fish. The size dependences of the TS values were TSmean = 20 log10 FL – 68.0, for both 38 and 120 kHz. This facilitated the estimation of biomass of young salmon using acoustic methods.

Nonstationary effects of ocean temperature on Pacific salmon productivity

2019 ◽  
Vol 76 (11) ◽  
pp. 1923-1928 ◽  
Author(s):  
Michael A. Litzow ◽  
Lorenzo Ciannelli ◽  
Curry J. Cunningham ◽  
Bethany Johnson ◽  
Patricia Puerta
Keyword(s):  
British Columbia ◽  
Bering Sea ◽  
Temperature Effects ◽  
Puget Sound ◽  
Gulf Of Alaska ◽  
Additive Models ◽  
Oncorhynchus Gorbuscha ◽  
Nonstationary Temperature ◽  
Oncorhynchus Keta ◽  
Ocean Temperature

We tested the hypothesis that ocean temperature effects on productivity for northeast Pacific pink (Oncorhynchus gorbuscha), sockeye (Oncorhynchus nerka), and chum salmon (Oncorhynchus keta) changed after 1988–1989, coincident with a decline in Aleutian Low variance. Nonstationary temperature effects were tested with three different analytical methods (correlation, mixed-effects models, and variable coefficient generalized additive models) applied to spawner–recruit time series from 86 wild runs between Puget Sound and the northern Bering Sea. All three methods supported the hypothesis, with evidence for change in temperature effects that was strongest in the Gulf of Alaska, British Columbia, and Washington and weakest in the Bering Sea. Productivity for all three species showed generally positive responses to ocean temperature in Alaska before 1988–1989, but generally neutral responses after 1988–1989. British Columbia and Washington salmon showed either neutral responses to temperature (pink), negative responses that weakened after 1988–1989 (sockeye), or a switch from neutral to negative responses (chum). We conclude that the inverse response of Alaskan and more southern salmon populations to temperature variability is a time-dependent phenomenon.

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